Concentrations

Part Per Hundred

• Represented by the percent (%) symbol

• 1 part per 100 parts

• 1 part in 102

• A value of 1 × 10-2

• Equivalent to about 15 minutes in one day

• Prefix: centi

• Symbol: c

Part Per Thousand

• 1 part per thousand should be spelled out in full and not as “ppt”

• Represented by the permille (‰) symbol. • 1 part per 1,000 parts• 1 part in 103

• A value of 1 × 10-3

• Equivalent to about 1 ½ minutes in a day• Prefix: milli• Symbol: m

Part Per Million

• 1 part per million (ppm) • 1 part per 1,000,000 parts• 1 part in 106

• A value of 1 × 10-6 • Equivalent to about 32 seconds out of a

year• Prefix: micro• Symbol:

Part Per Million

• A liter of water weighs 1,000 grams, and a milligram is 1/1,000th of a gram

• Therefore, a milligram of a substance dissolved in a liter of water represents one millionth (1,000 divided by 1/1,000) of the weight, or one part per million (1 ppm)

• One drop of water is 2 ppm of a bathtub full of water

Part Per Billion

• 1 part per billion (ppb) • 1 part per 1,000,000,000 parts• 1 part in 109

• A value of 1 × 10-9

• Equivalent to about 3 seconds out of a century• One drop of water is 1 ppb of a swimming pool

full of water• Prefix: nano• Symbol: n

Part Per Trillion

• 1 part per trillion (ppt)• 1 part per 1,000,000,000,000 parts• 1 part in 1012

• A value of 1 × 10-12

• This is equivalent to about 3 seconds out of every hundred thousand years

• Prefix: pico• Symbol: p

Part Per Quadrillion

• 1 part per quadrillion (ppq)• 1 part per 1,000,000,000,000,000 parts• 1 part in 1015

• A value of 1 × 10-15

• Equivalent to 2 ½ minutes out of the age of the Earth (4.5 billion years)

• Prefix: femto• Symbol: f

Practice Problems

1. How much is 6 ppm in ppb?

2. What concentration is 4,000 ppt in ppm?

6

1,000,000

1,000

1,000

6,000

1,000,000,0006,000 ppbx = =

4,000

1,000,000,000,000

1,000,000

1,000,000

0.004

1,000,0000.004 ppm÷ = =